On playgrounds and at playdates, it's hard to have a conversation about childhood immunizations without the word autism popping up. In fact, a recent study published in the journal Pediatrics showed that one in four parents is concerned that vaccines can cause autism. It's no wonder when the Internet and television airwaves are full of personal stories that raise a question about the link. But the study that started the autism vaccine scare was recently retracted by the prestigious journal that published it 12 years ago, and the lead researcher had his medical license pulled. Given these developments, some experts hope we have finally reached the end of the debate.
In 1998, a British gastroenterologist, Andrew Wakefield, M.D. and his colleagues published a paper in the British medical journal The Lancet suggesting that the measles, mumps, and rubella (MMR) vaccine might cause symptoms associated with autism. "Wakefield had a case study of eight children who had received the MMR and then developed symptoms of autism," says Paul Offit, MD, chief of infectious diseases at the Children's Hospital of Philadelphia. "He also believed they had abnormal intestinal tracts and proposed a syndrome -- linking intestinal inflammation from receiving the MMR with the development of autism."
Though Wakefield acknowledged in the paper that "he could not say whether the MMR caused autism," says Dr. Offit, "it opened the door for the notion that a vaccine could cause autism. It was the Royal Free Hospital, an excellent hospital in London, it was published in the oldest medical journal, and it was off to the races." In England, thousands of parents refused to vaccinate their children, resulting in hundreds of hospitalizations and three deaths in Ireland from measles.
What the Research Shows
Since that time, 18 controlled epidemiological studies have investigated the possible connection between autism and vaccines, and "they have all come back showing the same thing," says Alison Singer, founder and president of the Autism Science Foundation, and a mother of a 13-year-old with autism. "There is no link between vaccines and autism."
Those studies took up two primary theories: Wakefield's hypothesis that the MMR vaccine was linked to autism, and another that thimerosal, a mercury-containing preservative found in some vaccines, was the culprit. In a 2004 report analyzing the research into the possible connections, the Institute of Medicine (the organization charged with advising the nation on public health concerns) concluded: "the body of epidemiological evidence favors rejection of a causal relationship" between both the MMR vaccine and thimerosal, and autism. That same year, 10 of the 13 authors of the Wakefield study retracted it.
In February The Lancet, in an historic moment, retracted Wakefield's entire study after an independent government review concluded that he had acted "dishonestly and irresponsibly" in conducting his research. This included doing unnecessary and painful procedures on the children and not disclosing the fact that he had been paid as a consultant to two attorneys representing parents who believed their children had been harmed by the MMR vaccine. In May 2010, Wakefield was banned from practicing medicine in his native UK.
"This retraction represents the death of a hypothesis," says Offit. "Parents should be reassured that a choice not to get a vaccine will in no sense lessen the risk of autism, and will only increase the risk of disease."